Apparatus and methods for reducing embolization during treatment of carotid artery disease

ABSTRACT

Methods and apparatus are provided for removing emboli during an angioplasty, stenting or surgical procedure comprising a catheter having an occlusion element, an aspiration lumen, and a blood outlet port in communication with the lumen, a guide wire having a balloon, a venous return sheath with a blood inlet port, and tubing that couples the blood outlet port to the blood inlet port. Apparatus is also provided for occluding the external carotid artery to prevent reversal of flow into the internal carotid artery. The pressure differential between the artery and the vein provides reverse flow through the artery, thereby flushing emboli. A blood filter may optionally be included in-line with the tubing to filter emboli from blood reperfused into the patient.

REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 09/418,727, filed Oct. 15, 1999 now U.S. Pat. No.6,423,032, which is a continuation-in-part of U.S. patent applicationSer. No. 09/333,074, filed Jun. 14, 1999, now U.S. Pat. No. 6,206,868,which is a continuation-in-part of International ApplicationPCT/US99/05469, filed Mar. 12, 1999, which is a continuation-in-part ofU.S. patent application Ser. No. 09/078,263, filed May 13, 1998 now U.S.Pat. No. 6,413,235.

FIELD OF THE INVENTION

This invention relates to apparatus and methods for protecting againstembolization during vascular interventions, such as carotid arteryangioplasty and endarterectomy. More particularly, the apparatus andmethods of the present invention induce substantially continuousretrograde flow through the internal carotid artery during treatmentduring an interventional procedure, without significant blood loss.

BACKGROUND OF THE INVENTION

Carotid artery stenoses typically manifest in the common carotid artery,internal carotid artery or external carotid artery as a pathologicnarrowing of the vascular wall, for example, caused by the deposition ofplaque, that inhibits normal blood flow. Endarterectomy, an opensurgical procedure, traditionally has been used to treat such stenosisof the carotid artery.

An important problem encountered in carotid artery surgery is thatemboli may be formed during the course of the procedure, and theseemboli can rapidly pass into the cerebral vasculature and cause ischemicstroke.

In view of the trauma and long recuperation times generally associatedwith open surgical procedures, considerable interest has arisen in theendovascular treatment of carotid artery stenosis. In particular,widespread interest has arisen in transforming interventional techniquesdeveloped for treating coronary artery disease, such as angioplasty andstenting, for use in the carotid arteries. Such endovascular treatments,however, are especially prone to the formation of emboli.

Such emboli may be created, for example, when an interventionalinstrument, such as a guide wire or angioplasty balloon, is forcefullypassed into or through the stenosis, as well as after dilatation anddeflation of the angioplasty balloon or stent deployment. Because suchinstruments are advanced into the carotid artery in the same directionas blood flow, emboli generated by operation of the instruments arecarried directly to the brain by antegrade blood flow.

Stroke rates after carotid artery stenting have widely varied indifferent clinical series, from as low as 4.4% to as high as 30%. Onereview of carotid artery stenting including data from twenty-four majorinterventional centers in Europe, North America, South America and Asia,had a combined initial failure and combined mortality/stroke rate ofmore than 7%. Cognitive studies and reports of intellectual changesafter carotid artery stenting indicate that embolization is a commonevent causing subclinical cerebral damage.

Several previously known apparatus and methods attempt to remove emboliformed during endovascular procedures by trapping or suctioning theemboli out of the vessel of interest. These previously known systems,however, provide less than optimal solutions to the problems ofeffectively removing emboli.

Solano et al. U.S. Pat. No. 4,921,478 describes cerebral angioplastymethods and devices wherein two concentric shafts are coupled at adistal end to a distally-facing funnel-shaped structure. A lumen of theinnermost shaft communicates with an opening in the funnel-shapedstructure at the distal end, and is open to atmospheric pressure at theproximal end. In use, the funnel-shaped structure is deployed proximally(in the direction of flow) of a stenosis, occluding antegrade flow. Anangioplasty balloon catheter is passed through the innermost lumen andinto the stenosis, and then inflated to dilate the stenosis. The patentstates that when the angioplasty balloon is deflated, a pressuredifferential between atmospheric pressure and the blood distal to theangioplasty balloon causes a reversal of flow in the vessel that flushesany emboli created by the angioplasty balloon through the lumen of theinnermost catheter.

While a seemingly elegant solution to the problem of emboli removal,several drawbacks of the device and methods described in the Solano etal. patent seem to have lead to abandonment of that approach. Chiefamong these problems is the inability of that system to generate flowreversal during placement of the guide wire and the angioplasty balloonacross the stenosis. Because flow reversal does not occur until afterdeflation of the angioplasty balloon, there is a substantial risk thatany emboli created during placement of the angioplasty balloon willtravel too far downstream to be captured by the subsequent flowreversal. It is expected that this problem is further compounded becauseonly a relatively small volume of blood is removed by the pressuredifferential induced after deflation of the angioplasty balloon.

Applicant has determined another drawback of the method described in theSolano patent: deployment of the funnel-shaped structure in the commoncarotid artery (“CCA”) causes reversal of flow from the external carotidartery (“ECA”) into the internal carotid artery (“ICA”). Consequently,when a guide wire or interventional instrument is passed across a lesionin either the ECA or ICA, emboli dislodged from the stenosis areintroduced into the blood flow and carried into the cerebral vasculaturevia the ICA.

The insufficient flow drawback identified for the system of the Solanopatent is believed to have prevented development of a commercialembodiment of the similar system described in EP Publication No. 0 427429. EP Publication No. 0 427 429 describes use of a separate balloon toocclude the ECA prior to crossing the lesion in the ICA. However, likeSolano, that publication discloses that flow reversal occurs only whenthe dilatation balloon in the ICA is deflated.

Chapter 46 of Interventional Neuroradiology: strategies and practicaltechniques (J. J. Connors & J. Wojak, 1999), published by Saunders ofPhiladelphia, Pa., describes using a coaxial balloon angioplasty systemfor patients having proximal ICA stenoses. In particular, a small,deflated occlusion balloon on a wire is introduced into the origin ofthe ECA, and a guide catheter with a deflated occlusion balloon ispositioned in the CCA just proximal to the origin of the ECA. A dilationcatheter is advanced through a lumen of the guide catheter and dilatedto disrupt the stenosis. Before deflation of the dilation catheter, theocclusion balloons on the guide catheter and in the ECA are inflated toblock antegrade blood flow to the brain. The dilation balloon then isdeflated, the dilation catheter is removed, and blood is aspirated fromthe ICA to remove emboli.

Applicant has determined that cerebral damage still may result from theforegoing previously known procedure, which is similar to that describedin EP Publication No. 0 427 429, except that the ICA is occluded priorto the ECA. Consequently, both of these previously known systems andmethods suffer from the same drawback—the inability to generate flowreversal at sufficiently high volumes during placement of the guide wireand dilation catheter across the stenosis. Both methods entail asubstantial risk that any emboli created during placement of the balloonwill travel too far downstream to be captured by the flow reversal.

Applicants note, irrespective of the method of aspiration employed withthe method described in the foregoing Interventional Neuroradiologyarticle, substantial drawbacks are attendant. If, for example, naturalaspiration is used (i.e., induced by the pressure gradient between theatmosphere and the artery), then only a relatively small volume of bloodis expected to be removed by the pressure differential induced afterdeflation of the angioplasty balloon. If, on the other hand, an externalpump is utilized, retrieval of these downstream emboli may require aflow rate that cannot be sustained for more than a few seconds,resulting insufficient removal of emboli.

Furthermore, with the dilation balloon in position, the occlusionballoons are not inflated until after inflation of the dilation balloon.Microemboli generated during advancement of the dilation catheter intothe stenosed segment may therefore be carried by antegrade blood flowinto the brain before dilation, occlusion, and aspiration are evenattempted.

Imran U.S. Pat. No. 5,833,650 describes a system for treating stenosesthat comprises three concentric shafts. The outermost shaft includes aproximal balloon at its distal end that is deployed proximal of astenosis to occlude antegrade blood flow. A suction pump then drawssuction through a lumen in the outermost shaft to cause a reversal offlow in the vessel while the innermost shaft is passed across thestenosis. Once located distal to the stenosis, a distal balloon on theinnermost shaft is deployed to occlude flow distal to the stenosis.Autologous blood taken from a femoral artery using an extracorporealblood pump is infused through a central lumen of the innermost catheterto provide continued antegrade blood flow distal to the distal balloon.The third concentric shaft, which includes an angioplasty balloon, isthen advanced through the annulus between the innermost and outermostcatheters to dilate the stenosis.

Like the device of the Solano patent, the device of the Imran patentappears to suffer the drawback of potentially dislodging emboli that arecarried into the cerebral vasculature. In particular, once the distalballoon of Imran's innermost shaft is deployed, flow reversal in thevasculature distal to the distal balloon ceases, and the blood perfusedthrough the central lumen of the innermost shaft establishes antegradeflow. Importantly, if emboli are generated during deployment of thedistal balloon, those emboli will be carried by the perfused blooddirectly into the cerebral vasculature, and again pose a risk ofischemic stroke. Moreover, there is some evidence that reperfusion ofblood under pressure through a small diameter catheter may contribute tohemolysis and possible dislodgment of emboli.

In applicant's co-pending U.S. patent application Ser. No. 09/333,074,filed Jun. 14, 1999, which is incorporated herein by reference,applicant described the use of external suction to induce regionalreversal of flow. That application further described that intermittentlyinduced regional flow reversal overcomes the drawbacks ofnaturally-aspirated systems such as described hereinabove. However, theuse of external suction may in some instances result in flow rates thatare too high to be sustained for more than a few seconds. In addition,continuous use of an external pump may result in excessive blood loss,requiring infusion of non-autologous blood and/or saline that causeshemodilution, reduced blood pressure, or raise related safety issues.

In view of these drawbacks of the previously known emboli removalsystems, it would be desirable to provide methods and apparatus forremoving emboli from within the carotid arteries during interventionalprocedures, such as angioplasty or carotid stenting, that reduce therisk that emboli are carried into the cerebral vasculature.

It also would be desirable to provide methods and apparatus for removingemboli from within the carotid arteries during interventionalprocedures, such as angioplasty or carotid stenting, that providesubstantially continuous retrograde blood flow from the treatment zone,thereby reducing the risk that emboli are carried into the cerebralvasculature.

It further would be desirable to provide emboli removal methods andapparatus that prevent the development of reverse flow from the ECA andantegrade into the ICA once the CCA has been occluded, thereby enhancingthe likelihood that emboli generated by a surgical or interventionalprocedure are effectively removed from the vessel.

It also would be desirable to provide methods and apparatus that allowfor placement of an interventional device so that retrograde flow may beachieved in the treatment vessel prior to having a guide wire cross thelesion.

It also would be desirable to provide methods and apparatus for removingemboli during an angioplasty or carotid stenting procedure that enablefiltering of emboli and reduced blood loss.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of this invention to providemethods and apparatus for removing emboli from within the carotidarteries during interventional procedures, such as angioplasty orcarotid stenting, that reduce the risk that emboli are carried into thecerebral vasculature.

It also is an object of the present invention to provide methods andapparatus for removing emboli from within the carotid arteries duringinterventional procedures, such as angioplasty or carotid stenting, thatprovide substantially continuous retrograde blood flow from thetreatment zone, thereby reducing the risk that emboli are carried intothe cerebral vasculature.

It is another object of the present invention to provide emboli removalmethods and apparatus that prevent the development of reverse flowbetween the ECA and ICA once the common carotid artery has beenoccluded, thereby enhancing the likelihood that emboli generated by asurgical or interventional procedure are effectively removed from thevessel.

It is still a further object of the present to provide methods andapparatus that allow for placement of an interventional device so thatretrograde flow may be achieved in the treatment vessel prior to havinga guide wire cross the lesion.

It is yet another object of the present invention to provide methods andapparatus for removing emboli during an angioplasty or carotid stentingprocedure that enable filtering of emboli and reduced blood loss.

The foregoing objects of the present invention are accomplished byproviding interventional apparatus comprising an arterial catheter, anocclusion element disposed on a guide wire, a venous return sheath, andoptionally a blood filter. The arterial catheter has proximal and distalends, an aspiration lumen extending therethrough, an occlusion elementdisposed on the distal end, and a hemostatic port and blood outlet portdisposed on the proximal end that communicate with the aspiration lumen.The aspiration lumen is sized so that an interventional instrument,e.g., an angioplasty catheter or stent delivery system, may be readilyadvanced therethrough to the site of a stenosis in either the ECA(proximal to the occlusion element) or the ICA.

In accordance with the principles of the present invention, the arterialcatheter is disposed in the CCA proximal of the ICA/ECA bifurcation, theocclusion element on the guide wire is disposed in the ECA to occludeflow reversal from the ECA to the ICA, and the blood outlet port of thearterial catheter is coupled to the venous return sheath, with orwithout the blood filter disposed therebetween. Higher arterial thanvenous pressure, especially during diastole, permits substantiallycontinuous flow reversal in the ICA during the procedure (other thanwhen a dilatation balloon is inflated), thereby flushing bloodcontaining emboli from the vessel. The blood is filtered and reperfusedinto the body through the venous return sheath.

In an alternative embodiment, the occlusion element disposed on theguide wire may be omitted, and replaced with apparatus comprising aself-expanding element having proximal and distal ends, a retrieval wirecoupled to the proximal end and an atraumatic tip coupled to the distalend. In this embodiment, a dilator having a lumen may be disposed withinthe aspiration lumen of the catheter so that the occlusion element isprovided in a contracted state within the lumen of the dilator. Theocclusion element then is ejected from the dilator and self-expands toocclude the ECA. The dilator then is removed from the aspiration lumenof the catheter, and the distal end of the catheter is re-positioned inthe CCA proximal of the carotid bifurcation. Flow reversal is induced inthe ICA, as described above, and the self-expanding occlusion elementmay be contracted using the retrieval wire provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments, in which:

FIGS. 1A and 1B are schematic views of previously known emboliprotection systems;

FIG. 2 is a schematic view of an emboli protection system in accordancewith principles of the present invention;

FIGS. 3A-3D are, respectively, a schematic view of apparatus inaccordance with a first embodiment of the present invention, detailedside and sectional views of the distal end of an interventional deviceof the present invention, and a cross-sectional view of aninterventional device of the present invention;

FIGS. 4A and 4B are views of the distal end of an alternativeinterventional device suitable for use in the system of the presentinvention;

FIGS. 5A-5D illustrate a method of using the system of FIG. 3 inaccordance with the principles of the present invention;

FIGS. 6A-6C are, respectively, a schematic view and cross-sectionalviews of the proximal and distal ends of a catheter of an alternativeembodiment of the present invention;

FIGS. 7A-7B depict features of the self-expanding occlusion element ofFIGS. 6; and

FIGS. 8A-8D illustrate a method of using the system of FIGS. 6 inaccordance with the principles of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, drawbacks of previously known emboliremoval catheters are described with reference to performingpercutaneous angioplasty of stenosis S in common carotid artery CCA.

With respect to FIG. 1A, drawbacks associated with naturally-aspiratedemboli removal systems, such as described in the above-mentioned patentto Solano and European Patent Publication, are described. No flowreversal is induced by those systems until after balloon 10 ofangioplasty catheter 11 first is passed across the stenosis, inflated,and then deflated. However, applicant has determined that once member 15of emboli removal catheter 16 is inflated, flow within the ECA reversesand provides antegrade flow into the ICA, due to the lower hemodynamicresistance of the ICA. Consequently, emboli E generated while passingguide wire 20 or catheter 11 across stenosis S may be carriedirretrievably into the cerebral vasculature, before flow in the vesselis reversed and directed into the aspiration lumen of emboli removalcatheter 16 by opening the proximal end of the aspiration lumen toatmospheric pressure. Furthermore, natural-aspiration may not remove anadequate volume of blood to retrieve even those emboli that have not yetbeen carried all the way into the cerebral vasculature.

In FIG. 1B, system 17 described in the above-mentioned patent to Imranis shown. As described hereinabove, deployment of distal balloon 18, andejection of blood out of the distal end of the inner catheter, maydislodge emboli from the vessel wall distal to balloon 18. Theintroduction of antegrade flow through inner catheter 19 is expectedonly to exacerbate the problem by pushing the emboli further into thecerebral vasculature. Thus, while the use of positive suction in theImran system may remove emboli located in the confined treatment fielddefined by the proximal and distal balloons, such suction is notexpected to provide any benefit for emboli dislodged distal of distalballoon 18.

Referring now to FIG. 2, apparatus and methods in accordance with thepresent invention are described. Apparatus 30 comprises catheter 31having an aspiration lumen and occlusion element 32, and guide wire 35having inflatable balloon 36 disposed on its distal end. In accordancewith the principles of the present invention, antegrade blood flow isstopped when both occlusion element 32 in the CCA and inflatable balloon36 are deployed. Furthermore, the aspiration lumen of catheter 31 isconnected to a venous return sheath (described hereinbelow), disposed,for example, in the patient's femoral vein. In this manner asubstantially continuous flow of blood is induced between the treatmentsite and the patient's venous vasculature. Because flow through theartery is towards catheter 31, any emboli dislodged by advancing a guidewire or angioplasty catheter 33 across stenosis S causes the emboli tobe aspirated by catheter 31.

Unlike the previously known naturally-aspirated systems, the presentinvention provides substantially continuous retrograde blood flowthrough the ICA while preventing blood from flowing retrograde in theECA and antegrade into the ICA, thereby preventing emboli from beingcarried into the cerebral vasculature. Because the apparatus and methodsof the present invention “recycle” emboli-laden blood from the arterialcatheter through the blood filter and to the venous return sheath, thepatient experiences significantly less blood loss.

Referring now to FIG. 3A, embolic protection apparatus 40 constructed inaccordance with the principles of the present invention is described.Apparatus 40 comprises arterial catheter 41, guide wire 45, venousreturn sheath 52, tubing 49 and optional blood filter 50.

Catheter 41 includes distal occlusion element 42, proximal hemostaticport 43, e.g., a Touhy-Borst connector, inflation port 44, and bloodoutlet port 48. Guide wire 45 includes balloon 46 that is inflated viainflation port 47. Tubing 49 couples blood outlet port 48 to filter 50and blood inlet port 51 of venous return sheath 52.

Guide wire 45 and balloon 46 are configured to pass through hemostaticport 43 and the aspiration lumen of catheter 41 (see FIGS. 3C and 3D),so that the balloon may be advanced into and occlude the ECA. Port 43and the aspiration lumen of catheter 41 are sized to permit additionalinterventional devices, such as angioplasty balloon catheters,atherectomy devices and stent delivery systems to be advanced throughthe aspiration lumen when guide wire 45 is deployed.

Guide wire 45 preferably comprises a small diameter flexible shafthaving an inflation lumen that couples inflatable balloon 46 toinflation port 47. Inflatable balloon 46 preferably comprises acompliant material, such as described hereinbelow with respect toocclusion element 42 of emboli removal catheter 41.

Venous return sheath 52 includes hemostatic port 53, blood inlet port 51and a lumen that communicates with ports 53 and 51 and tip 54. Venousreturn sheath 52 may be constructed in a manner per se known for venousintroducer catheters. Tubing 49 may comprise a suitable length of abiocompatible material, such as silicone. Alternatively, tubing 49 maybe omitted and blood outlet port 48 of catheter 41 and blood inlet port51 of venous return sheath 52 may be lengthened to engage either end offilter 50 or each other.

With respect to FIGS. 3B and 3C, distal occlusion element 42 comprisesexpandable bell or pear-shaped balloon 55. In accordance withmanufacturing techniques that are known in the art, balloon 55 comprisesa compliant material, such as polyurethane, latex or polyisoprene whichhas variable thickness along its length to provide a bell-shape wheninflated. Balloon 55 is affixed to distal end 56 of catheter 41, forexample, by gluing or a melt-bond, so that opening 57 in balloon 55leads into aspiration lumen 58 of catheter 41. Balloon 55 preferably iswrapped and heat treated during manufacture so that distal portion 59 ofthe balloon extends beyond the distal end of catheter 41 and provides anatraumatic tip or bumper for the catheter.

As shown in FIG. 3D, catheter 41 preferably comprises inner layer 60 oflow-friction material, such as polytetrafluoroethylene (“PTFE”), coveredwith a layer of flat stainless steel wire braid 61 and polymer cover 62(e.g., polyurethane, polyethylene, or PEBAX). Inflation lumen 63 isdisposed within polymer cover 62 and couples inflation port 44 toballoon 55. In a preferred embodiment of catheter 41, the diameter oflumen 58 is about 7 Fr, and the outer diameter of the catheter is about9 Fr.

Referring now to FIGS. 4A and 4B, an alternative embodiment of occlusionelement 42 of the system of FIG. 3A is described. In FIGS. 4A and 4B,occlusion element 42 of emboli removal catheter 41 comprisesself-expanding wire basket 65 covered with elastomeric polymer 66, suchas latex, polyurethane or polyisoprene. Alternatively, a tightly knitself-expanding wire mesh may be used, with or without an elastomericcovering.

Catheter 41 is contained within movable sheath 67. Catheter 41 isinserted transluminally with sheath 67 in a distalmost position, andafter basket 65 has been determined to be in a desired position proximalto a stenosis, sheath 67 is retracted proximally to cause basket 65 todeploy. Upon completion of the procedure, basket 65 is again collapsedwithin sheath 67 by moving the sheath to its distalmost position.Operation of the system of FIG. 3A using the emboli removal catheter ofFIGS. 4A and 4B is similar to that described hereinbelow for FIGS.5A-5D, except that the occlusion element self-expands when sheath 67 isretracted, rather than by infusing an inflation medium to balloon 55.

Referring now to FIGS. 5A-5D, use of the apparatus of FIG. 3 inaccordance with the methods of the present invention is described. InFIG. 5, stenosis S is located in internal carotid artery ICA above thebifurcation between the ICA and the external carotid artery ECA. In afirst step, guide wire 80 is inserted into a patient's arterialvasculature and a distal end of guide wire 80 preferably is disposedjust proximal of the carotid bifurcation, as shown in FIG. 5A. A dilator(not shown), which is disposed within catheter 41, then may be insertedover guide wire 80 to advance catheter 41 to a position proximal ofstenosis S, as shown in FIG. 5A, and the dilator may be removed. Balloon55 of distal occlusion element 42 then is inflated via inflation port44, preferably using a radiopaque contrast solution, and guide wire 80may be removed. Once balloon 55 of distal occlusion element 42 isinflated, flow within the ECA reverses and provides antegrade flow intothe ICA, as shown in FIG. 5A, due to the lower hemodynamic resistance ofthe ICA.

Venous return sheath 52 then is introduced into the patient's femoralvein, either percutaneously or via a surgical cut-down. Filter 50 thenis coupled between blood outlet port 48 of catheter 41 and blood inletport 51 of venous return sheath 52 using tubing 49, and any air isremoved from the line. Once this circuit is closed, negative pressure inthe venous sheath during diastole will establish a low rate continuousflow of blood through aspiration lumen 58 of catheter 41, to thepatient's vein via venous return sheath 52.

Guide wire 45 and balloon 46 then may be advanced through aspirationlumen 58. When balloon 46 is disposed within the ECA, as determined,e.g., using a fluoroscope and a radiopaque inflation medium injectedinto balloon 46, balloon 46 is inflated. The deployment of balloon 46 inthe ECA, in conjunction with the negative pressure in the venous sheathduring diastole, will established a retrograde flow dynamic in the ICA,as shown in FIG. 5B.

This continuous retrograde flow in the ICA due to the difference betweenvenous pressure and arterial pressure will continue throughout theinterventional procedure. Specifically, blood passes through aspirationlumen 58 and blood outlet port 48 of catheter 41, through biocompatibletubing 49 to filter 50, and into blood inlet port 51 of venous returnsheath 52, where it is reperfused into the remote vein. Filtered embolicollect in filter 50 and may be studied and characterized uponcompletion of the procedure.

Continuous blood flow (except during inflation of any dilatationinstruments) with reperfusion in accordance with the present inventionprovides efficient emboli removal with significantly reduced blood loss.Alternatively, filter 50 may be omitted, in which case emboli removedfrom the arterial side will be introduced into the venous side, andeventually captured in the lungs. Because of a low incidence of septaldefects, which could permit such emboli to cross-over to the leftventricle, the use of filter 50 is preferred.

Referring to FIG. 5C, an interventional instrument, such as conventionalangioplasty balloon catheter 71 having balloon 72, is loaded throughhemostatic port 43 and aspiration lumen 58 and positioned within thestenosis, preferably via guide wire 73. Hemostatic port 43 is closed andinstrument 71 is actuated to disrupt the plaque forming stenosis S.

As seen in FIG. 5D, upon completion of the angioplasty portion of theprocedure using catheter 71, balloon 72 is deflated. Throughout theprocedure, except when the dilatation balloon is fully inflated, thepressure differential between the blood in the ICA and the venouspressure causes blood in the ICA to flow in a retrograde direction intoaspiration lumen 58 of emboli removal catheter 41, thereby flushing anyemboli from the vessel. The blood is filtered and reperfused into thepatient's vein.

As set forth above, the method of the present invention protects againstembolization, first, by preventing the reversal of blood flow from theECA to the ICA when distal occlusion element 42 is inflated, and second,by providing continuous, low volume blood flow from the carotid arteryto the remote vein in order to filter and flush any emboli from thevessel and blood stream. Advantageously, the method of the presentinvention permits emboli to be removed with little blood loss, becausethe blood is filtered and reperfused into the patient. Furthermore,continuous removal of blood containing emboli prevents emboli frommigrating too far downstream for aspiration.

Referring now to FIG. 6, apparatus 240 constructed in accordance withthe present invention is described. Apparatus 240 is an alternativeembodiment of apparatus 40 described hereinabove and comprises arterialcatheter 241 having proximal and distal ends, distal occlusion element242 disposed on the distal end, proximal hemostatic port 243, inflationport 244 and blood outlet port 248. Self-expanding occlusion element 246having proximal and distal ends preferably comprises non-expandingocclusion base 256 disposed at the proximal end, wherein occlusion base256 comprises proximal taper 269. Occlusion element 246 is coupled toretrieval wire 247 at the proximal end and atraumatic tip 245 at thedistal end, e.g., by affixing retrieval wire 247 to proximal taper 269of occlusion base 256 and affixing atraumatic tip 245 to a distal end ofocclusion base 256, as shown in FIG. 6A. Biocompatible tubing 249couples blood outlet port 248 to filter 250 and to blood inlet port 251of venous return sheath 252. Arterial catheter 241, venous return sheath252 and tubing 249 are constructed as described hereinabove, except asnoted below.

Catheter 241 comprises aspiration lumen 258, as shown in FIG. GB, whichis sized to permit interventional devices, such as angioplasty ballooncatheters, atherectomy devices and stent delivery systems to be advancedthrough port 243 and the aspiration lumen. Retrieval wire lumen 264 issized to permit longitudinal movement of retrieval wire 247 of occlusionelement 246. Retrieval wire lumen 264 spans from the proximal end ofcatheter 241 to a location just proximal of the distal end, e.g., about1 to 2 cm proximal of the distal end of catheter 241. At this location,retrieval wire lumen 264 merges with aspiration lumen 258 to formchannel 265, as shown in FIG. 6C.

Referring to FIG. 7, deployment of occlusion element 246 is described.Occlusion element 246 initially is provided in a contracted state, asshown in FIG. 7A. In the contracted state, occlusion element 246 isdisposed within a lumen of dilator 270, which in turn is disposed withinaspiration lumen 258 of catheter 241. Dilator 270 comprises proximal anddistal ends, with occlusion element 246 being positioned within a slotin the distal end. The distal end of dilator 270 tapers and extendsdistal to catheter 241, as shown in FIG. 7A. Atraumatic tip 245 ofocclusion element 246 extends distal to dilator 270 and facilitatesguidance of the device through a patient's vasculature.

Push member 272 having proximal and distal ends is configured forlongitudinal movement within the lumen of dilator 270. During deliveryof catheter 241, the distal end of push member 272 preferably abutsocclusion base 256 of occlusion element 246, while the proximal end ofpush member 272 may be manipulated by a physician. Dilator 270 comprisesslot 271 disposed at the distal end. Slot 271 allows retrieval wire 247to extend from a distal point in which it is coupled to occlusion base256, to a proximal point in which it enters retrieval wire lumen 264, asshown in FIG. 7A.

Upon positioning the distal end of catheter 241 at a selected location,push member 272 is held stationary while dilator 270 is retractedproximally, so that occlusion element 246 effectively is no longerconstrained within the lumen of dilator 270. This causes occlusionelement 246 to self-expand to a predetermined shape, as shown in FIG.7B. Occlusion element 246 is sized to occlude flow in the externalcarotid artery in this deployed state.

Dilator slot 271 allows retrieval wire 247 to move freely during thedeployment of occlusion element 246. After deployment of occlusionelement 246, dilator 270 and push member 272 are removed from withinaspiration lumen 258, as shown in FIG. 7B. Catheter 241 then may bepositioned separately from occlusion element 246, as describedhereinbelow with respect to FIG. 8, and may be used to deliver otherinterventional apparatus, such as angioplasty catheters or stentdelivery systems.

At the completion of the interventional procedure, occlusion element 246is contracted by proximally retracting retrieval wire 247. Occlusionelement 246 is retrieved when the proximal load exerted on retrievalwire 247 exceeds the frictional forces between occlusion element 246 andthe external carotid artery wall. After occlusion element 246 iscontracted, occlusion base 256, occlusion element 246 and atraumatic tip245 may be retracted partially or fully into aspiration lumen 258.Channel 265 of FIG. 6C may be used to provide a transition at the distalend of catheter 241 so that occlusion element 246 is effectively guidedinto aspiration lumen 258 when retrieval wire 247 is retractedproximally. In effect, this allows occlusion element 246 to be containedwithin at least a distal portion of catheter 241, to allow for saferemoval of catheter 241.

Referring to FIG. 8, method steps for using the apparatus of FIGS. 6-7to treat carotid artery disease is provided. In FIG. 8, stenosis S islocated in the ICA above the carotid bifurcation. In a first step,catheter 241 is inserted, either percutaneously and transluminally orvia a surgical cut-down, to a position proximal of stenosis S. Occlusionelement 246 is disposed within a lumen at the distal end of dilator 270,as described in FIG. 7A, and atraumatic tip 245 is used to guidecatheter 241. The distal end of catheter 241 preferably is positionedwithin the ECA, as shown in FIG. 8A, so that occlusion element 246 willbe deployed into the ECA.

Push member 272 of FIG. 7A then is held stationary while dilator 270 isretracted proximally, so that occlusion element 246 is no longerconstrained by dilator 270. Occlusion element 246 then self-expands toocclude flow in the ECA, as shown in FIG. 8B. Dilator 270 and pushmember 272 then are removed from within aspiration lumen 258, andcatheter 241 is retracted to a location just proximal of the carotidbifurcation, as shown in FIG. 8B. Distal occlusion element 242 ofcatheter 241 then may be inflated via inflation port 244 to occludeantegrade flow in the CCA.

Venous return sheath 252 may be introduced into the patient's femoralvein, either percutaneously or via a surgical cut-down, and filter 250may be coupled between blood outlet port 248 of catheter 241 and bloodinlet port 251 of venous return sheath 252 using tubing 249. Once thiscircuit is closed, negative pressure in the venous sheath establishes acontinuous retrograde flow of blood through aspiration lumen 258 ofcatheter 241, as shown in FIG. 8B, to the patient's vein via venousreturn sheath 252. Alternatively, venous return sheath 252 may beomitted, and the proximal end of catheter 241 connected to a receptacleto collect blood aspirated through aspiration lumen 258.

Referring to FIG. 8C, with distal occlusion element 242 inflated and aretrograde flow established in the ICA, an interventional instrument,such as conventional angioplasty balloon catheter 281 having balloon282, is loaded through hemostatic port 243 and aspiration lumen 258 andpositioned within stenosis S, preferably via guide wire 283. Hemostaticport 243 is closed and instrument 281 is actuated to disrupt stenosis S.

As shown in FIG. 8D, upon completion of the angioplasty portion of theprocedure using catheter 281, balloon 282 is deflated. Throughout theprocedure, except when the dilatation balloon is fully inflated, thepressure differential between the blood in the ICA and the venouspressure causes blood in the ICA to flow in a retrograde direction andinto aspiration lumen 258 of emboli removal catheter 241, therebyflushing any emboli E from the vessel.

Upon satisfactory removal of emboli, occlusion element 246 is contractedby proximally retracting retrieval wire 247. Occlusion element 246 stillfurther may be contracted when it contacts the distal end of catheter241. When occlusion element 246 has been contracted, it then may beretracted either partially or fully into aspiration lumen 258 ofcatheter 241 via channel 265. Distal occlusion element 242 of catheter241 then is deflated and the apparatus is removed from the patient'svessel.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to one skilled in the art that variouschanges and modifications may be made. The appended claims are intendedto cover all such changes and modifications that fall within the truespirit and scope of the invention.

1. Apparatus for removing emboli during an angioplasty or stentingprocedure from a vessel having a trunk portion coupled to first andsecond branches via a bifurcation, the apparatus comprising: a catheterhaving proximal and distal ends, a first lumen extending therethrough, ablood outlet port in communication with the first lumen, and a distalocclusion element disposed on the distal end of the catheter, thecatheter adapted to be disposed in a patient's trunk portion proximal tothe bifurcation; and an occlusion member having proximal and distalends, the occlusion member comprising a self-expanding blood impermeableelement, a retrieval wire coupled to the proximal end of the occlusionmember and an atraumatic tip coupled to the distal end of the occlusionmember, wherein the occlusion member further comprises a contractedstate and a deployed state in which the self expanding blood impermeableelement is configured to substantially prevent flow in one of the firstand second branch vessels.
 2. The apparatus of claim 1 wherein theocclusion member is configured to occlude flow in an external carotidartery in the deployed state.
 3. The apparatus of claim 1 wherein thedistal occlusion element is an inflatable member.
 4. The apparatus ofclaim 1 further comprising: a venous return sheath having proximal anddistal ends, a lumen extending therethrough, and a blood inlet port incommunication with the lumen; and tubing that couples the blood outletport of the catheter to the blood inlet port of the venous returnsheath.
 5. The apparatus of claim 4 further comprising a blood filterdisposed between the blood outlet port of the catheter and the bloodinlet port of the venous return sheath.
 6. The apparatus of claim 1further comprising a dilator having proximal and distal ends and a lumenextending therethrough, wherein the dilator is configured to be disposedwithin the first lumen of the catheter.
 7. The apparatus of claim 6wherein the occlusion member is adapted to be disposed within the lumenof the dilator in the contracted state.
 8. The apparatus of claim 6wherein the dilator comprises a slot at the distal end that isconfigured to permit movement of the retrieval wire within the slot. 9.The apparatus of claim 6 further comprising a push member havingproximal and distal ends, wherein the push member is configured forlongitudinal movement within the lumen of the dilator.
 10. The apparatusof claim 9 wherein the distal end of the push member configured to abutthe proximal end of the occlusion member within the lumen of thedilator.
 11. The apparatus of claim 1 wherein the proximal end of theocclusion member comprises a taper.
 12. The apparatus of claim 1 furthercomprising a second lumen, wherein the retrieval wire is configured forlongitudinal movement within the second lumen.
 13. The apparatus ofclaim 12 wherein the second lumen merges with the first lumen along aportion of the distal end of the catheter.
 14. Apparatus for removingemboli from a carotid artery during an angioplasty or stentingprocedure, the apparatus comprising: a catheter having proximal anddistal ends, a first lumen extending therethrough, a blood outlet portin communication with the first lumen, and a distal occlusion elementdisposed on the distal end of the catheter, the catheter adapted to bedisposed in a patient's common carotid artery; and an occlusion memberhaving proximal and distal ends, the occlusion member comprising aplurality of self-expanding struts carrying a blood impermeable element,a retrieval wire coupled to the proximal end of the occlusion member andan atraumatic tip coupled to the distal end of the occlusion member,wherein the occlusion member further comprises a contracted state and adeployed state in which the self-expanding blood impermeable element isconfigured to substantially prevent flow in one of either an internalcarotid artery or an external carotid artery.
 15. The apparatus of claim14 wherein the occlusion member is configured to occlude flow in anexternal carotid artery in the deployed state.
 16. The apparatus ofclaim 14 wherein the distal occlusion element is an inflatable member.17. The apparatus of claim 14 further comprising: a venous return sheathhaving proximal and distal ends, a lumen extending therethrough, and ablood inlet port in communication with the lumen, and tubing thatcouples the blood outlet port of the catheter to the blood inlet port ofthe venous return sheath.
 18. The apparatus of claim 17 furthercomprising a blood filter disposed between the blood outlet port of thecatheter and the blood inlet port of the venous return sheath.
 19. Theapparatus of claim 14 further comprising a dilator having proximal anddistal ends and a lumen extending therethrough, wherein the dilator isconfigured to be disposed within the first lumen of the catheter. 20.The apparatus of claim 19 wherein the occlusion member is adapted to bedisposed within the lumen of the dilator in the contracted state. 21.The apparatus of claim 19 wherein the dilator comprises a slot at thedistal end that is configured to permit movement of the retrieval wirewithin the slot.
 22. The apparatus of claim 19 further comprising a pushmember having proximal and distal ends, wherein the push member isconfigured for longitudinal movement within the lumen of the dilator.23. The apparatus of claim 22 wherein the distal end of the push memberis configured to abut the proximal end of the occlusion member withinthe lumen of the dilator.
 24. The apparatus claim 14 wherein theproximal end of the occlusion member comprises a taper.
 25. Theapparatus of claim 14 further comprising a second lumen, wherein theretrieval wire is configured for longitudinal movement within the secondlumen.
 26. The apparatus of claim 25 wherein the second lumen mergeswith the first lumen along a portion of the distal end of the catheter.